Why and how are some questions deleted?

Questions that are extremely off topic, or of very low quality, may be removed at the discretion of the community and moderators.

Over time, closed questions that are not useful as signpoints to other questions may also be removed, as well as questions which have no significant activity over a very long period after being asked. If you want to improve a question to keep it from being deleted, click the edit button beneath it. See How to Ask for more tips on improving questions.

Users can delete their own questions if the question:

has zero answers

has only one answer, but that answer has no upvotes

has no bounties that were awarded to any answer that isn't already deleted

Simply click the delete link underneath the question.

Questions can also be deleted by the community. Moderators can delete any question, and users with sufficient reputation can cast delete votes on closed questions. It takes 3 votes, minimum, to delete a closed question. However, the number of delete votes required scales to the number of votes on the question and all its answers. Questions that have been closed within the past 48 hours cannot be deleted, so as to allow for editing and possible reopening.

Additionally, any question that accumulates enough offensive or spam flags will be automatically deleted.

What happens when a post is deleted?

Once a post has been deleted, it will disappear for all users except developers, moderators, and users with over 2,000 reputation. Deleted questions and answers are always visible to their authors, regardless of the author's reputation.

Self-deleted questions can be viewed and undeleted by their original authors.
If you delete your own question, you must undelete it before you are able to edit it.

Please note that deleted questions do not appear in search results, so if you wish to later undelete a question that you've deleted you must have saved the URL somewhere.